This invention relates to a device for perforating a web or sheet of material made of paper, plastic, metal, fabric or other like materials, and includes a rotatable male die carrier roll having at least one radially extending bore opening into the outer periphery thereof for the reception of a removable and interchangeable male die member held in place within a hollow cylinder removably and interchangeably received within the bore.
Devices of this type are employed to punch holes into the web or sheet of material, the holes normally being circular although they may possibly be of square or triangular shape.
The holes may define feed holes for feeding the web or sheet through a web or sheet processing machine such as a cutter, high speed printer, etc. Otherwise, the punched holes may facilitate the fastening together or superposed webs or sheets, or may facilitate other applications.
U.S. Pat. No. 1,649,635 discloses a perforating device which comprises a pair of cooperating rolls having outer, axially extending grooves for the reception of male and female die holders and inserts for positioning the holders predetermined distances from one another in the grooves. The holders are of T-shaped cross-section and are therefore costly to produce. Moreover, the dies, especially the male dies, are not easily exchangeable or removable from the holders.
Another perforating device is disclosed in U.S. Pat. No. 3,706,250 in which male dies are interchangeable in a corresponding cylindrical roll. However, the cylindrical roll is designed in such a manner that only male dies with the same geometric dimensions can be interchanged.